The suspension system of a land vehicle typically includes multiple shock absorbers that are connected between the sprung mass of the vehicle and unsprung mass of the vehicle. Shock absorbers absorb unwanted vibrations that occur during movement of the suspension system.
Generally shock absorbers for vehicles such as automobiles are hydraulic shock absorbers that comprise a tubular body having a piston that divides the interior of the body into an upper working chamber and a lower working chamber. The tubular body is attached to the vehicle wheel assembly (unsprung mass) and the outwardly extending end of a piston rod is connected to the body of the vehicle (sprung mass).
Such shock absorbers are generally either of a twin tube or mono tube design. The monotube shock absorber comprises a single pressure tube. The piston has compression valving which limits the flow of damping fluid from the lower working chamber to the upper working chamber during a compression stroke and rebound valving which limits the flow of damping fluid from the upper working chamber to the lower working chamber during a rebound stroke. The compression and rebound valving of the piston produce the damping force which counteracts the vibration which would otherwise be transmitted from the unsprung mass to the sprung mass.
The twin tube shock absorber has a reserve tube located around the pressure tube to form a reservoir there between. In typical twin tube shock absorbers a base valve assembly is positioned between the lower working chamber and the fluid reservoir to control the flow of damping fluid. The compression valving and the rebound valving is located in the base valve assembly. The piston of the shock absorber reciprocates inside the working chamber of the tubular body as the vehicle moves. The piston comprises apertures that allows restricted fluid flow between the upper and lower working chambers. Negative and positive pressure within the lower working chamber forces damping fluid respectively through the rebound valving or the compression valving out of and into the fluid reservoir.
It is an object of the present invention to harness energy from damping fluid flows of the compression stroke and rebound stroke.
It is another object of a specific aspect of this invention to harness energy in a shock absorber from pressure differences between the upper working chamber and the lower working chamber using a turbine to convert the same to electrical energy.
There have been several attempts to convert energy from suspension systems of vehicles to electrical energy. U.S. Pat. No. 3,507,580 takes off the pressure of the damping fluid of the shock absorber to feed to a remote pressure driven motor coupled with a remote electricity generator. U.S. Pat. No. 6,920,951, U.S. Pat. No. 8,541,895 and US patent publication 20080290624 utilise in line reciprocal movement of the piston rod relative to a stator to generate electricity, and US Patent publication 20070089919 utilises a remote reciprocal electricity generator coupled with the piston to generate electricity. U.S. Pat. No. 8,376,100 discloses a further suggestion that takes off the pressure of the damping fluid of the shock absorber to feed a remote pressure driven electricity generator. The hydraulic motor of this prior publication has a number of limitations, requiring several one-way valves and conduits to route the flow of fluid and a fluid reservoir to dampen the suspension system and inhibit freewheeling of the hydraulic motor. The use of several one-way valves increases the chance for failure, while the multiple conduits and fluid reservoir makes the system difficult to fit in a simple manner to existing shock absorber configurations.
It is desirable to have a generator that is compact and can be fitted to a shock absorber tube without the need for a remote generator.
It should be appreciated that any discussion of the prior art throughout the specification is included solely for the purpose of providing a context for the present invention and should in no way be considered as an admission that such prior art was widely known or formed part of the common general knowledge in the field as it existed before the priority date of the application.